100 /	SPECIAL (X) PATCHES TO FOCAL
 110 
 120 /	LAST EDIT:	28-JAN-1988	11:00:00	CJL
 130 
 140 /	MAY BE ASSEMBLED WITH '/J' SWITCH SET.
 150 
 160 /	THIS FILE IS A ONE-PAGE COLLECTION OF PATCHES TO FOCAL TO IMPLEMENT THREE
 170 /	FUNCTIONS:
 180 
 190 /	1):	FBLK(BLOCK[,WRITE-INDICATOR])
 200 /	2):	FWRD(ADDRESS[,REPLACEMENT VALUE])
 210 /	3):	FAND(FIRST-ARGUMENT[,SECOND-ARGUMENT])
 220 
 230 /	DESCRIPTION OF FUNCTIONS:
 240 
 250 /	FUNCTION "FBLK" READS (OR WRITES) A SET OF DISK BLOCKS STARTING FROM THE
 260 /	BLOCK NUMBER EVALUATED FROM THE FIRST ARGUMENT. THE FUNCTION WILL CAUSE
 270 /	A READ OPERATION IF ONE ARGUMENT IS GIVEN; MERELY GIVING A SECOND
 280 /	ARGUMENT CAUSES A WRITE OPERATION (THE ARGUMENT VALUE IS UNIMPORTANT).
 290 /	THE MEMORY AFFECTED BY THE TRANSFER IS LOCATION 0000 ONWARD IN FIELD
 300 /	"BUFFLD." THE NUMBER OF BLOCKS TRANSFERRED IS DETERMINED BY "N." THE
 310 /	LOGICAL I/O UNIT IS DETERMINED BY "UNIT."
 320 
 330 /	FUNCTION "FWRD" RETURNS THE CONTENTS OF THE SPECIFIED MEMORY ADDRESS
 340 /	EVALUATED FROM THE FIRST ARGUMENT. IF A SECOND ARGUMENT IS PASSED, THEN
 350 /	ITS EVALUATION BECOMES THE REPLACEMENT VALUE AT THE SPECIFIED ADDRESS. IF
 360 /	THE FIRST ARGUMENT IS IN THE RANGE 0000-4095, THE FIRST ARGUMENT REFERS
 370 /	TO THE 4096 ELEMENTS IN FIELD "BUFFLD." THIS CORRESPONDS TO THE BUFFER
 380 /	DEFINED IN THE "FBLK" FUNCTION. IF THE FIRST ARGUMENT IS IN THE RANGE
 390 /	4096-6143, THE FIRST ARGUMENT REFERS TO AN ARRAY OF DOUBLE-PRECISION
 400 /	ELEMENTS IN THE NEXT FIELD PAST "BUFFLD." THESE ELEMENTS ARE UNRELATED TO
 410 /	THE "FBLK" FUNCTION AND ARE USED INDEPENDENTLY.
 420 
 430 /	FUNCTION "FAND" RETURNS THE LOGICAL BIT-WISE AND OF THE TWO ARGUMENTS
 440 /	PASSED TO IT. IF THE SECOND ARGUMENT IS NOT PRESENT, IT IS TREATED AS
 450 /	ZERO AND CAUSES A ZERO RETURN VALUE.
 460 
 470 /	ASSEMBLY INSTRUCTIONS:
 480 
 490 /	SET "BUFFLD" TO THE PROPER FIELD FOR "FBLK", "FWRD" (DEFAULT IS 40).
 500 
 510 /	SET "N" TO THE I/O CALL LENGTH DESIRED IN "FBLK" (DEFAULT IS 00 WHICH
 520 /	USES 40 BLOCKS).
 530 
 540 /	SET "UNIT" TO THE DESIRED I/O UNIT (DEFAULT IS 7).
 550 	EJECT
 560 /	DEFINITIONS FROM FOCAL, 1969 (ORIGINAL PAPER-TAPE VERSION).
 570 
 580 	BOTTOM=	0035			/FOCAL PUSHDOWN LIMIT
 590 	CHAR=	0066			/FOCAL'S INPUT BUFFER
 600 	EFUN3I=	0136			/FUNCTION RETURN POINTER
 610 	EVAL=	1613			/EVALUATOR ENTRY POINT
 620 	FLAC=	0044			/FLOATING ACCUMULATOR HERE
 630 	FNTABF=	0374			/FUNCTION ADDRESS TABLE
 640 	FNTABL=	2165			/HASHED FUNCTION NAME TABLE
 650 	INTEGER=0053			/FLOATING TO FIXED CONVERSION POINTER
 660 	POPA=	TAD I	13		/REMOVE WORD FROM STACK
 670 	POPJ=	JMP I	141		/REMOVE AND RETURN FROM STACK
 680 	PUSHA=	JMS I	142		/PUSH WORD ONTO STACK
 690 	PUSHJ=	JMS I	140		/CALL WITH RETURN ON STACK
 700 	P7600=	0104			/CONSTANT 7600
 710 	RETURN=	JMP I	EFUN3I		/FUNCTION RETURN INSTRUCTION
 720 
 730 /	DEFINITIONS FROM P?S/8 FOCAL OVERLAY.
 740 
 750 	BEOFZAP=7505			/BINARY LOADER ZAP WORD
 760 	BONCE=	3600			/OVERLAY ONCE-ONLY ADDRESS
 770 	SYSIO=	7640			/SYSTEM I/O ENTRY POINT
 780 
 790 /	MISCELLANEOUS DEFINITIONS.
 800 
 810 	IFNDEF	BUFFLD	<BUFFLD=40>	/BUFFER FIELD FOR FBLK AND FWRD
 820 	IFNDEF	N	<N=	00>	/DO 40 BLOCK READ/WRITE CALLS FOR FBLK
 830 	NL0001=	CLA IAC			/LOAD AC WITH 0001
 840 	NL4000=	CLA CLL CML RAR		/SET AC TO 4000
 850 	NSTART=	4043			/PATCH ASSEMBLY ADDRESS
 860 	IFNDEF	UNIT	<UNIT=	7>	/I/O UNIT FOR FBLK
 870 
 880 	FIELD	0			/ENSURE FIELD ZERO
 890 
 900 	*FNTABL+14			/PUT IN HASHED NAMES
 910 
 920 	"B^2+"L^2+"K			/BLK
 930 	"W^2+"R^2+"D			/WRD
 940 	"A^2+"N^2+"D			/AND
 950 	EJECT